RabbitMQ is a message broker, a piece of software that can be used to pass messages between systems - or between components of systems. By doing this via a message broker, we can accomplish loose coupling and asynchronous interaction. As an added bonus, we can see the messages passed between the systems in a uniform way, which helps diagnosis when an error occurs.

As the name suggests, the book does indeed go in depth. It explains not just how to use RabbitMQ, but goes so far as to explain the strucuture of the messages sent. It contains examples in Python, but one does not need to know Python to benefit from the book.

RabbitMQ implements the AMQP protocol; however, it also offers some functionality beyond that. The book points out what parts of RabbitMQ are AMQP, and what parts are extensions. This is useful if there's a chance you'll be using another implementation of AMQP at some point.

All in all, I've found this book useful for my work.